The transformation can be represented using matrix math on a 3x3 array. * Given (x,y), the transformation (x',y') can be found by: *
* [ x'] [ m00 m01 m02 ] [ x ] [ m00*x + m01*y + m02 ] * [ y'] = [ m10 m11 m12 ] [ y ] = [ m10*x + m11*y + m12 ] * [ 1 ] [ 0 0 1 ] [ 1 ] [ 1 ] ** The bottom row of the matrix is constant, so a transform can be uniquely * represented (as in toString) by "[[m00, m01, m02], [m10, m11, m12]]". * * @author Tom Tromey
* [ 1 0 0 ] * [ 0 1 0 ] * [ 0 0 1 ] **/ public AffineTransform() { m00 = m11 = 1; } /** * Create a new transform which copies the given one. * * @param tx the transform to copy * @throws NullPointerException if tx is null */ public AffineTransform(AffineTransform tx) { setTransform(tx); } /** * Construct a transform with the given matrix entries: *
* [ m00 m01 m02 ] * [ m10 m11 m12 ] * [ 0 0 1 ] ** * @param m00 the x scaling component * @param m10 the y shearing component * @param m01 the x shearing component * @param m11 the y scaling component * @param m02 the x translation component * @param m12 the y translation component */ public AffineTransform(float m00, float m10, float m01, float m11, float m02, float m12) { this.m00 = m00; this.m10 = m10; this.m01 = m01; this.m11 = m11; this.m02 = m02; this.m12 = m12; updateType(); } /** * Construct a transform from a sequence of float entries. The array must * have at least 4 entries, which has a translation factor of 0; or 6 * entries, for specifying all parameters: *
* [ f[0] f[2] (f[4]) ] * [ f[1] f[3] (f[5]) ] * [ 0 0 1 ] ** * @param f the matrix to copy from, with at least 4 (6) entries * @throws NullPointerException if f is null * @throws ArrayIndexOutOfBoundsException if f is too small */ public AffineTransform(float[] f) { m00 = f[0]; m10 = f[1]; m01 = f[2]; m11 = f[3]; if (f.length >= 6) { m02 = f[4]; m12 = f[5]; } updateType(); } /** * Construct a transform with the given matrix entries: *
* [ m00 m01 m02 ] * [ m10 m11 m12 ] * [ 0 0 1 ] ** * @param m00 the x scaling component * @param m10 the y shearing component * @param m01 the x shearing component * @param m11 the y scaling component * @param m02 the x translation component * @param m12 the y translation component */ public AffineTransform(double m00, double m10, double m01, double m11, double m02, double m12) { this.m00 = m00; this.m10 = m10; this.m01 = m01; this.m11 = m11; this.m02 = m02; this.m12 = m12; updateType(); } /** * Construct a transform from a sequence of double entries. The array must * have at least 4 entries, which has a translation factor of 0; or 6 * entries, for specifying all parameters: *
* [ d[0] d[2] (d[4]) ] * [ d[1] d[3] (d[5]) ] * [ 0 0 1 ] ** * @param d the matrix to copy from, with at least 4 (6) entries * @throws NullPointerException if d is null * @throws ArrayIndexOutOfBoundsException if d is too small */ public AffineTransform(double[] d) { m00 = d[0]; m10 = d[1]; m01 = d[2]; m11 = d[3]; if (d.length >= 6) { m02 = d[4]; m12 = d[5]; } updateType(); } /** * Returns a translation transform: *
* [ 1 0 tx ] * [ 0 1 ty ] * [ 0 0 1 ] ** * @param tx the x translation distance * @param ty the y translation distance * @return the translating transform */ public static AffineTransform getTranslateInstance(double tx, double ty) { AffineTransform t = new AffineTransform(); t.setToTranslation(tx, ty); return t; } /** * Returns a rotation transform. A positive angle (in radians) rotates * the positive x-axis to the positive y-axis: *
* [ cos(theta) -sin(theta) 0 ] * [ sin(theta) cos(theta) 0 ] * [ 0 0 1 ] ** * @param theta the rotation angle * @return the rotating transform */ public static AffineTransform getRotateInstance(double theta) { AffineTransform t = new AffineTransform(); t.setToRotation(theta); return t; } /** * Returns a rotation transform about a point. A positive angle (in radians) * rotates the positive x-axis to the positive y-axis. This is the same * as calling: *
* AffineTransform tx = new AffineTransform(); * tx.setToTranslation(x, y); * tx.rotate(theta); * tx.translate(-x, -y); ** *
The resulting matrix is: *
* [ cos(theta) -sin(theta) x-x*cos+y*sin ] * [ sin(theta) cos(theta) y-x*sin-y*cos ] * [ 0 0 1 ] ** * @param theta the rotation angle * @param x the x coordinate of the pivot point * @param y the y coordinate of the pivot point * @return the rotating transform */ public static AffineTransform getRotateInstance(double theta, double x, double y) { AffineTransform t = new AffineTransform(); t.setToTranslation(x, y); t.rotate(theta); t.translate(-x, -y); return t; } /** * Returns a scaling transform: *
* [ sx 0 0 ] * [ 0 sy 0 ] * [ 0 0 1 ] ** * @param sx the x scaling factor * @param sy the y scaling factor * @return the scaling transform */ public static AffineTransform getScaleInstance(double sx, double sy) { AffineTransform t = new AffineTransform(); t.setToScale(sx, sy); return t; } /** * Returns a shearing transform (points are shifted in the x direction based * on a factor of their y coordinate, and in the y direction as a factor of * their x coordinate): *
* [ 1 shx 0 ] * [ shy 1 0 ] * [ 0 0 1 ] ** * @param shx the x shearing factor * @param shy the y shearing factor * @return the shearing transform */ public static AffineTransform getShearInstance(double shx, double shy) { AffineTransform t = new AffineTransform(); t.setToShear(shx, shy); return t; } /** * Returns the type of this transform. The result is always valid, although * it may not be the simplest interpretation (in other words, there are * sequences of transforms which reduce to something simpler, which this * does not always detect). The result is either TYPE_GENERAL_TRANSFORM, * or a bit-wise combination of TYPE_TRANSLATION, the mutually exclusive * TYPE_*_ROTATIONs, and the mutually exclusive TYPE_*_SCALEs. * * @see #TYPE_IDENTITY * @see #TYPE_TRANSLATION * @see #TYPE_UNIFORM_SCALE * @see #TYPE_GENERAL_SCALE * @see #TYPE_QUADRANT_ROTATION * @see #TYPE_GENERAL_ROTATION * @see #TYPE_GENERAL_TRANSFORM */ public int getType() { return type; } /** * Return the determinant of this transform matrix. If the determinant is * non-zero, the transform is invertible; otherwise operations which require * an inverse throw a NoninvertibleTransformException. A result very near * zero, due to rounding errors, may indicate that inversion results do not * carry enough precision to be meaningful. * *
If this is a uniform scale transformation, the determinant also * represents the squared value of the scale. Otherwise, it carries little * additional meaning. The determinant is calculated as: *
* | m00 m01 m02 | * | m10 m11 m12 | = m00 * m11 - m01 * m10 * | 0 0 1 | ** * @return the determinant * @see #createInverse() */ public double getDeterminant() { return m00 * m11 - m01 * m10; } /** * Return the matrix of values used in this transform. If the matrix has * fewer than 6 entries, only the scale and shear factors are returned; * otherwise the translation factors are copied as well. The resulting * values are: *
* [ d[0] d[2] (d[4]) ] * [ d[1] d[3] (d[5]) ] * [ 0 0 1 ] ** * @param d the matrix to store the results into; with 4 (6) entries * @throws NullPointerException if d is null * @throws ArrayIndexOutOfBoundsException if d is too small */ public void getMatrix(double[] d) { d[0] = m00; d[1] = m10; d[2] = m01; d[3] = m11; if (d.length >= 6) { d[4] = m02; d[5] = m12; } } /** * Returns the X coordinate scaling factor of the matrix. * * @return m00 * @see #getMatrix(double[]) */ public double getScaleX() { return m00; } /** * Returns the Y coordinate scaling factor of the matrix. * * @return m11 * @see #getMatrix(double[]) */ public double getScaleY() { return m11; } /** * Returns the X coordinate shearing factor of the matrix. * * @return m01 * @see #getMatrix(double[]) */ public double getShearX() { return m01; } /** * Returns the Y coordinate shearing factor of the matrix. * * @return m10 * @see #getMatrix(double[]) */ public double getShearY() { return m10; } /** * Returns the X coordinate translation factor of the matrix. * * @return m02 * @see #getMatrix(double[]) */ public double getTranslateX() { return m02; } /** * Returns the Y coordinate translation factor of the matrix. * * @return m12 * @see #getMatrix(double[]) */ public double getTranslateY() { return m12; } /** * Concatenate a translation onto this transform. This is equivalent, but * more efficient than *
concatenate(AffineTransform.getTranslateInstance(tx, ty)).
*
* @param tx the x translation distance
* @param ty the y translation distance
* @see #getTranslateInstance(double, double)
* @see #concatenate(AffineTransform)
*/
public void translate(double tx, double ty)
{
m02 += tx * m00 + ty * m01;
m12 += tx * m10 + ty * m11;
updateType();
}
/**
* Concatenate a rotation onto this transform. This is equivalent, but
* more efficient than
* concatenate(AffineTransform.getRotateInstance(theta)).
*
* @param theta the rotation angle
* @see #getRotateInstance(double)
* @see #concatenate(AffineTransform)
*/
public void rotate(double theta)
{
double c = Math.cos(theta);
double s = Math.sin(theta);
double n00 = m00 * c + m01 * s;
double n01 = m00 * -s + m01 * c;
double n10 = m10 * c + m11 * s;
double n11 = m10 * -s + m11 * c;
m00 = n00;
m01 = n01;
m10 = n10;
m11 = n11;
updateType();
}
/**
* Concatenate a rotation about a point onto this transform. This is
* equivalent, but more efficient than
* concatenate(AffineTransform.getRotateInstance(theta, x, y)).
*
* @param theta the rotation angle
* @param x the x coordinate of the pivot point
* @param y the y coordinate of the pivot point
* @see #getRotateInstance(double, double, double)
* @see #concatenate(AffineTransform)
*/
public void rotate(double theta, double x, double y)
{
translate(x, y);
rotate(theta);
translate(-x, -y);
}
/**
* Concatenate a scale onto this transform. This is equivalent, but more
* efficient than
* concatenate(AffineTransform.getScaleInstance(sx, sy)).
*
* @param sx the x scaling factor
* @param sy the y scaling factor
* @see #getScaleInstance(double, double)
* @see #concatenate(AffineTransform)
*/
public void scale(double sx, double sy)
{
m00 *= sx;
m01 *= sy;
m10 *= sx;
m11 *= sy;
updateType();
}
/**
* Concatenate a shearing onto this transform. This is equivalent, but more
* efficient than
* concatenate(AffineTransform.getShearInstance(sx, sy)).
*
* @param shx the x shearing factor
* @param shy the y shearing factor
* @see #getShearInstance(double, double)
* @see #concatenate(AffineTransform)
*/
public void shear(double shx, double shy)
{
double n00 = m00 + shx * m01;
double n01 = shx * m00 + m01;
double n10 = m10 * shy + m11;
double n11 = shx * m10 + m11;
m00 = n00;
m01 = n01;
m10 = n10;
m11 = n11;
updateType();
}
/**
* Reset this transform to the identity (no transformation):
* * [ 1 0 0 ] * [ 0 1 0 ] * [ 0 0 1 ] **/ public void setToIdentity() { m00 = m11 = 1; m01 = m02 = m10 = m12 = 0; type = TYPE_IDENTITY; } /** * Set this transform to a translation: *
* [ 1 0 tx ] * [ 0 1 ty ] * [ 0 0 1 ] ** * @param tx the x translation distance * @param ty the y translation distance */ public void setToTranslation(double tx, double ty) { m00 = m11 = 1; m01 = m10 = 0; m02 = tx; m12 = ty; type = (tx == 0 && ty == 0) ? TYPE_UNIFORM_SCALE : TYPE_TRANSLATION; } /** * Set this transform to a rotation. A positive angle (in radians) rotates * the positive x-axis to the positive y-axis: *
* [ cos(theta) -sin(theta) 0 ] * [ sin(theta) cos(theta) 0 ] * [ 0 0 1 ] ** * @param theta the rotation angle */ public void setToRotation(double theta) { double c = Math.cos(theta); double s = Math.sin(theta); m00 = c; m01 = -s; m02 = 0; m10 = s; m11 = c; m12 = 0; type = (c == 1 ? TYPE_IDENTITY : c == 0 || c == -1 ? TYPE_QUADRANT_ROTATION : TYPE_GENERAL_ROTATION); } /** * Set this transform to a rotation about a point. A positive angle (in * radians) rotates the positive x-axis to the positive y-axis. This is the * same as calling: *
* tx.setToTranslation(x, y); * tx.rotate(theta); * tx.translate(-x, -y); ** *
The resulting matrix is: *
* [ cos(theta) -sin(theta) x-x*cos+y*sin ] * [ sin(theta) cos(theta) y-x*sin-y*cos ] * [ 0 0 1 ] ** * @param theta the rotation angle * @param x the x coordinate of the pivot point * @param y the y coordinate of the pivot point */ public void setToRotation(double theta, double x, double y) { double c = Math.cos(theta); double s = Math.sin(theta); m00 = c; m01 = -s; m02 = x - x * c + y * s; m10 = s; m11 = c; m12 = y - x * s - y * c; updateType(); } /** * Set this transform to a scale: *
* [ sx 0 0 ] * [ 0 sy 0 ] * [ 0 0 1 ] ** * @param sx the x scaling factor * @param sy the y scaling factor */ public void setToScale(double sx, double sy) { m00 = sx; m01 = m02 = m10 = m12 = 0; m11 = sy; type = (sx != sy ? TYPE_GENERAL_SCALE : sx == 1 ? TYPE_IDENTITY : TYPE_UNIFORM_SCALE); } /** * Set this transform to a shear (points are shifted in the x direction based * on a factor of their y coordinate, and in the y direction as a factor of * their x coordinate): *
* [ 1 shx 0 ] * [ shy 1 0 ] * [ 0 0 1 ] ** * @param shx the x shearing factor * @param shy the y shearing factor */ public void setToShear(double shx, double shy) { m00 = m11 = 1; m01 = shx; m10 = shy; m02 = m12 = 0; updateType(); } /** * Set this transform to a copy of the given one. * * @param tx the transform to copy * @throws NullPointerException if tx is null */ public void setTransform(AffineTransform tx) { m00 = tx.m00; m01 = tx.m01; m02 = tx.m02; m10 = tx.m10; m11 = tx.m11; m12 = tx.m12; type = tx.type; } /** * Set this transform to the given values: *
* [ m00 m01 m02 ] * [ m10 m11 m12 ] * [ 0 0 1 ] ** * @param m00 the x scaling component * @param m10 the y shearing component * @param m01 the x shearing component * @param m11 the y scaling component * @param m02 the x translation component * @param m12 the y translation component */ public void setTransform(double m00, double m10, double m01, double m11, double m02, double m12) { this.m00 = m00; this.m10 = m10; this.m01 = m01; this.m11 = m11; this.m02 = m02; this.m12 = m12; updateType(); } /** * Set this transform to the result of performing the original version of * this followed by tx. This is commonly used when chaining transformations * from one space to another. In matrix form: *
* [ this ] = [ this ] x [ tx ] ** * @param tx the transform to concatenate * @throws NullPointerException if tx is null * @see #preConcatenate(AffineTransform) */ public void concatenate(AffineTransform tx) { double n00 = m00 * tx.m00 + m01 * tx.m10; double n01 = m00 * tx.m01 + m01 * tx.m11; double n02 = m00 * tx.m02 + m01 * tx.m12 + m02; double n10 = m10 * tx.m00 + m11 * tx.m10; double n11 = m10 * tx.m01 + m11 * tx.m11; double n12 = m10 * tx.m02 + m11 * tx.m12 + m12; m00 = n00; m01 = n01; m02 = n02; m10 = n10; m11 = n11; m12 = n12; updateType(); } /** * Set this transform to the result of performing tx followed by the * original version of this. This is less common than normal concatenation, * but can still be used to chain transformations from one space to another. * In matrix form: *
* [ this ] = [ tx ] x [ this ] ** * @param tx the transform to concatenate * @throws NullPointerException if tx is null * @see #concatenate(AffineTransform) */ public void preConcatenate(AffineTransform tx) { double n00 = tx.m00 * m00 + tx.m01 * m10; double n01 = tx.m00 * m01 + tx.m01 * m11; double n02 = tx.m00 * m02 + tx.m01 * m12 + tx.m02; double n10 = tx.m10 * m00 + tx.m11 * m10; double n11 = tx.m10 * m01 + tx.m11 * m11; double n12 = tx.m10 * m02 + tx.m11 * m12 + tx.m12; m00 = n00; m01 = n01; m02 = n02; m10 = n10; m11 = n11; m12 = n12; updateType(); } /** * Returns a transform, which if concatenated to this one, will result in * the identity transform. This is useful for undoing transformations, but * is only possible if the original transform has an inverse (ie. does not * map multiple points to the same line or point). A transform exists only * if getDeterminant() has a non-zero value. * * @return a new inverse transform * @throws NoninvertibleTransformException if inversion is not possible * @see #getDeterminant() */ public AffineTransform createInverse() throws NoninvertibleTransformException { double det = getDeterminant(); if (det == 0) throw new NoninvertibleTransformException("can't invert transform"); return new AffineTransform(m11 / det, -m10 / det, m01 / det, -m00 / det, -m02, -m12); } /** * Perform this transformation on the given source point, and store the * result in the destination (creating it if necessary). It is safe for * src and dst to be the same. * * @param src the source point * @param dst the destination, or null * @return the transformation of src, in dst if it was non-null * @throws NullPointerException if src is null */ public Point2D transform(Point2D src, Point2D dst) { if (dst == null) dst = new Point2D.Double(); double x = src.getX(); double y = src.getY(); double nx = m00 * x + m01 * y + m02; double ny = m10 * x + m11 * y + m12; dst.setLocation(nx, ny); return dst; } /** * Perform this transformation on an array of points, storing the results * in another (possibly same) array. This will not create a destination * array, but will create points for the null entries of the destination. * The transformation is done sequentially. While having a single source * and destination point be the same is safe, you should be aware that * duplicate references to the same point in the source, and having the * source overlap the destination, may result in your source points changing * from a previous transform before it is their turn to be evaluated. * * @param src the array of source points * @param srcOff the starting offset into src * @param dst the array of destination points (may have null entries) * @param dstOff the starting offset into dst * @param num the number of points to transform * @throws NullPointerException if src or dst is null, or src has null * entries * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded * @throws ArrayStoreException if new points are incompatible with dst */ public void transform(Point2D[] src, int srcOff, Point2D[] dst, int dstOff, int num) { while (--num >= 0) dst[dstOff] = transform(src[srcOff++], dst[dstOff++]); } /** * Perform this transformation on an array of points, in (x,y) pairs, * storing the results in another (possibly same) array. This will not * create a destination array. All sources are copied before the * transformation, so that no result will overwrite a point that has not yet * been evaluated. * * @param src the array of source points * @param srcOff the starting offset into src * @param dst the array of destination points * @param dstOff the starting offset into dst * @param num the number of points to transform * @throws NullPointerException if src or dst is null * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded */ public void transform(float[] srcPts, int srcOff, float[] dstPts, int dstOff, int num) { if (srcPts == dstPts && dstOff > srcOff && num > 1 && srcOff + 2 * num > dstOff) { float[] f = new float[2 * num]; System.arraycopy(srcPts, srcOff, f, 0, 2 * num); srcPts = f; } while (--num >= 0) { float x = srcPts[srcOff++]; float y = srcPts[srcOff++]; dstPts[dstOff++] = (float) (m00 * x + m01 * y + m02); dstPts[dstOff++] = (float) (m10 * x + m10 * y + m12); } } /** * Perform this transformation on an array of points, in (x,y) pairs, * storing the results in another (possibly same) array. This will not * create a destination array. All sources are copied before the * transformation, so that no result will overwrite a point that has not yet * been evaluated. * * @param src the array of source points * @param srcOff the starting offset into src * @param dst the array of destination points * @param dstOff the starting offset into dst * @param num the number of points to transform * @throws NullPointerException if src or dst is null * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded */ public void transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int num) { if (srcPts == dstPts && dstOff > srcOff && num > 1 && srcOff + 2 * num > dstOff) { double[] d = new double[2 * num]; System.arraycopy(srcPts, srcOff, d, 0, 2 * num); srcPts = d; } while (--num >= 0) { double x = srcPts[srcOff++]; double y = srcPts[srcOff++]; dstPts[dstOff++] = m00 * x + m01 * y + m02; dstPts[dstOff++] = m10 * x + m10 * y + m12; } } /** * Perform this transformation on an array of points, in (x,y) pairs, * storing the results in another array. This will not create a destination * array. * * @param src the array of source points * @param srcOff the starting offset into src * @param dst the array of destination points * @param dstOff the starting offset into dst * @param num the number of points to transform * @throws NullPointerException if src or dst is null * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded */ public void transform(float[] srcPts, int srcOff, double[] dstPts, int dstOff, int num) { while (--num >= 0) { float x = srcPts[srcOff++]; float y = srcPts[srcOff++]; dstPts[dstOff++] = m00 * x + m01 * y + m02; dstPts[dstOff++] = m10 * x + m10 * y + m12; } } /** * Perform this transformation on an array of points, in (x,y) pairs, * storing the results in another array. This will not create a destination * array. * * @param src the array of source points * @param srcOff the starting offset into src * @param dst the array of destination points * @param dstOff the starting offset into dst * @param num the number of points to transform * @throws NullPointerException if src or dst is null * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded */ public void transform(double[] srcPts, int srcOff, float[] dstPts, int dstOff, int num) { while (--num >= 0) { double x = srcPts[srcOff++]; double y = srcPts[srcOff++]; dstPts[dstOff++] = (float) (m00 * x + m01 * y + m02); dstPts[dstOff++] = (float) (m10 * x + m10 * y + m12); } } /** * Perform the inverse of this transformation on the given source point, * and store the result in the destination (creating it if necessary). It * is safe for src and dst to be the same. * * @param src the source point * @param dst the destination, or null * @return the inverse transformation of src, in dst if it was non-null * @throws NullPointerException if src is null * @throws NoninvertibleTransformException if the inverse does not exist * @see #getDeterminant() */ public Point2D inverseTransform(Point2D src, Point2D dst) throws NoninvertibleTransformException { double det = getDeterminant(); if (det == 0) throw new NoninvertibleTransformException("couldn't invert transform"); if (dst == null) dst = new Point2D.Double(); double x = src.getX(); double y = src.getY(); double nx = (m11 * x + -m10 * y) / det - m02; double ny = (m01 * x + -m00 * y) / det - m12; dst.setLocation(nx, ny); return dst; } /** * Perform the inverse of this transformation on an array of points, in * (x,y) pairs, storing the results in another (possibly same) array. This * will not create a destination array. All sources are copied before the * transformation, so that no result will overwrite a point that has not yet * been evaluated. * * @param src the array of source points * @param srcOff the starting offset into src * @param dst the array of destination points * @param dstOff the starting offset into dst * @param num the number of points to transform * @throws NullPointerException if src or dst is null * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded * @throws NoninvertibleTransformException if the inverse does not exist * @see #getDeterminant() */ public void inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int num) throws NoninvertibleTransformException { double det = getDeterminant(); if (det == 0) throw new NoninvertibleTransformException("couldn't invert transform"); if (srcPts == dstPts && dstOff > srcOff && num > 1 && srcOff + 2 * num > dstOff) { double[] d = new double[2 * num]; System.arraycopy(srcPts, srcOff, d, 0, 2 * num); srcPts = d; } while (--num >= 0) { double x = srcPts[srcOff++]; double y = srcPts[srcOff++]; dstPts[dstOff++] = (m11 * x + -m10 * y) / det - m02; dstPts[dstOff++] = (m01 * x + -m00 * y) / det - m12; } } /** * Perform this transformation, less any translation, on the given source * point, and store the result in the destination (creating it if * necessary). It is safe for src and dst to be the same. The reduced * transform is equivalent to: *
* [ x' ] = [ m00 m01 ] [ x ] = [ m00 * x + m01 * y ] * [ y' ] [ m10 m11 ] [ y ] = [ m10 * x + m11 * y ] ** * @param src the source point * @param dst the destination, or null * @return the delta transformation of src, in dst if it was non-null * @throws NullPointerException if src is null */ public Point2D deltaTransform(Point2D src, Point2D dst) { if (dst == null) dst = new Point2D.Double(); double x = src.getX(); double y = src.getY(); double nx = m00 * x + m01 * y; double ny = m10 * x + m11 * y; dst.setLocation(nx, ny); return dst; } /** * Perform this transformation, less any translation, on an array of points, * in (x,y) pairs, storing the results in another (possibly same) array. * This will not create a destination array. All sources are copied before * the transformation, so that no result will overwrite a point that has * not yet been evaluated. The reduced transform is equivalent to: *
* [ x' ] = [ m00 m01 ] [ x ] = [ m00 * x + m01 * y ] * [ y' ] [ m10 m11 ] [ y ] = [ m10 * x + m11 * y ] ** * @param src the array of source points * @param srcOff the starting offset into src * @param dst the array of destination points * @param dstOff the starting offset into dst * @param num the number of points to transform * @throws NullPointerException if src or dst is null * @throws ArrayIndexOutOfBoundsException if array bounds are exceeded */ public void deltaTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int num) { if (srcPts == dstPts && dstOff > srcOff && num > 1 && srcOff + 2 * num > dstOff) { double[] d = new double[2 * num]; System.arraycopy(srcPts, srcOff, d, 0, 2 * num); srcPts = d; } while (--num >= 0) { double x = srcPts[srcOff++]; double y = srcPts[srcOff++]; dstPts[dstOff++] = m00 * x + m01 * y; dstPts[dstOff++] = m10 * x + m11 * y; } } /** * Return a new Shape, based on the given one, where the path of the shape * has been transformed by this transform. Notice that this uses GeneralPath, * which only stores points in float precision. * * @param src the shape source to transform * @return the shape, transformed by this * @throws NullPointerException if src is null * @see GeneralPath#transform(AffineTransform) */ public Shape createTransformedShape(Shape src) { GeneralPath p = new GeneralPath(src); p.transform(this); return p; } /** * Returns a string representation of the transform, in the format: *
"AffineTransform[[" + m00 + ", " + m01 + ", " + m02 + "], ["
* + m10 + ", " + m11 + ", " + m12 + "]]".
*
* @return the string representation
*/
public String toString()
{
return "AffineTransform[[" + m00 + ", " + m01 + ", " + m02 + "], ["
+ m10 + ", " + m11 + ", " + m12 + "]]";
}
/**
* Tests if this transformation is the identity:
* * [ 1 0 0 ] * [ 0 1 0 ] * [ 0 0 1 ] ** * @return true if this is the identity transform */ public boolean isIdentity() { // Rather than rely on type, check explicitly. return (m00 == 1 && m01 == 0 && m02 == 0 && m10 == 0 && m11 == 1 && m12 == 0); } /** * Create a new transform of the same run-time type, with the same * transforming properties as this one. * * @return the clone */ public Object clone() { try { return super.clone(); } catch (CloneNotSupportedException e) { throw (Error) new InternalError().initCause(e); // Impossible } } /** * Return the hashcode for this transformation. The formula is not * documented, but appears to be the same as: *
* long l = Double.doubleToLongBits(getScaleX()); * l = l * 31 + Double.doubleToLongBits(getShearY()); * l = l * 31 + Double.doubleToLongBits(getShearX()); * l = l * 31 + Double.doubleToLongBits(getScaleY()); * l = l * 31 + Double.doubleToLongBits(getTranslateX()); * l = l * 31 + Double.doubleToLongBits(getTranslateY()); * return (int) ((l >> 32) ^ l); ** * @return the hashcode */ public int hashCode() { long l = Double.doubleToLongBits(m00); l = l * 31 + Double.doubleToLongBits(m10); l = l * 31 + Double.doubleToLongBits(m01); l = l * 31 + Double.doubleToLongBits(m11); l = l * 31 + Double.doubleToLongBits(m02); l = l * 31 + Double.doubleToLongBits(m12); return (int) ((l >> 32) ^ l); } /** * Compares two transforms for equality. This returns true if they have the * same matrix values. * * @param o the transform to compare * @return true if it is equal */ public boolean equals(Object obj) { if (! (obj instanceof AffineTransform)) return false; AffineTransform t = (AffineTransform) obj; return (m00 == t.m00 && m01 == t.m01 && m02 == t.m02 && m10 == t.m10 && m11 == t.m11 && m12 == t.m12); } /** * Helper to decode the type from the matrix. This is not guaranteed * to find the optimal type, but at least it will be valid. */ private void updateType() { double det = getDeterminant(); if (det == 0) { type = TYPE_GENERAL_TRANSFORM; return; } // Scale (includes rotation by PI) or translation. if (m01 == 0 && m10 == 0) { if (m00 == m11) type = m00 == 1 ? TYPE_IDENTITY : TYPE_UNIFORM_SCALE; else type = TYPE_GENERAL_SCALE; if (m02 != 0 || m12 != 0) type |= TYPE_TRANSLATION; } // Rotation. else if (m00 == m11 && m01 == -m10) { type = m00 == 0 ? TYPE_QUADRANT_ROTATION : TYPE_GENERAL_ROTATION; if (det != 1) type |= TYPE_UNIFORM_SCALE; if (m02 != 0 || m12 != 0) type |= TYPE_TRANSLATION; } else type = TYPE_GENERAL_TRANSFORM; } /** * Reads a transform from an object stream. * * @param s the stream to read from * @throws ClassNotFoundException if there is a problem deserializing * @throws IOException if there is a problem deserializing */ private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException { s.defaultReadObject(); updateType(); } } // class AffineTransform